James K. Polk

James Knox Polk (2 November 1795-15 June 1849) was President of the United States from 4 March 1845 to 4 March 1849, succeeding John Tyler and preceding Zachary Taylor. He previously served as a member of the US House of Representatives (DR-TN 6) from 4 March 1825 to 3 March 1833 (succeeding John Alexander Cocke and preceding Balie Peyton) and from TN-9 from 4 March 1833 to 3 March 1839 (succeeding William Fitzgerald and preceding Harvey Magee Watterson) and Governor of Tennessee from 14 October 1839 to 15 October 1841 (succeeding Newton Cannon and preceding James C. Jones).

Biography
James Knox Polk was born in Pineville, North Carolina in 1795 to a Presbyterian Scots-Irish family of farmers, and his father led the family to Columbia, Maury County, Tennessee in 1806. Polk was elected clerk of the Tennessee State Senate in 1819, serving until 1822. He also became a successful lawyer, and he went on to serve in the US House of Representatives from 1825 to 1839 and as Governor from 1839 to 1841. He was a strong supporter of Andrew Jackson, and, in 1844, he became the dark horse Democratic candidate for President. He was endorsed by sitting President John Tyler due to his support for Manifest Destiny, and he defeated Whig candidate Henry Clay.

Presidency
In the first year of his presidency, Polk reached a settlement with the United Kingdom over Oregon, splitting the territory along the 49th Parallel and annexing the majority of its lands. That same year, he also agreed to the annexation of the Republic of Texas as a state, and, when Mexico refused to sell the United States the disputed Texan territory between the Rio Grande and the Nueces River, Polk sent troops to the Rio Grande, leading to a clash with the Mexican Army which started the Mexican-American War in 1846. The ensuing three-year war led to the United States' annexation of the entire American West, with the Rio Grande as its southernmost border and the Pacific Ocean as its westermost border, completing Manifest Destiny's goal of building a nation "from sea to shining sea". Also in 1846, he reduced tariff rates and re-established the Independent Treasury system. He fulfilled his promise to only serve one term, and he left office in 1849, with Mexican-American War hero Zachary Taylor winning the presidency. Polk died just three months after leaving the White House.